Study of Turbulent Fluctuations Driven by the Electron Temperature Gradient in the National Spherical Torus Experiment

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Various theories and numerical simulations support the conjecture that the ubiquitous problem of anomalous electron transport in tokamaks may arise from a short-scale turbulence driven by the electron temperature gradient. To check whether this turbulence is present in plasmas of the National Spherical Torus Experiment (NSTX), measurements of turbulent fluctuations were performed with coherent scattering of electromagnetic waves. Results from plasmas heated by high harmonic fast waves (HHFW) show the existence of density fluctuations in the range of wave numbers k⊥ρe=0.1-0.4, corresponding to a turbulence scale length of the order of the collisionless skin depth. Experimental observations and agreement with ... continued below

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Mazzucato, E.; Bell, R. E.; Ethier, S.; Hosea, J. C.; Kaye, S. M.; LeBlanc, B. P. et al. March 26, 2009.

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Various theories and numerical simulations support the conjecture that the ubiquitous problem of anomalous electron transport in tokamaks may arise from a short-scale turbulence driven by the electron temperature gradient. To check whether this turbulence is present in plasmas of the National Spherical Torus Experiment (NSTX), measurements of turbulent fluctuations were performed with coherent scattering of electromagnetic waves. Results from plasmas heated by high harmonic fast waves (HHFW) show the existence of density fluctuations in the range of wave numbers k⊥ρe=0.1-0.4, corresponding to a turbulence scale length of the order of the collisionless skin depth. Experimental observations and agreement with numerical results from the linear gyro-kinetic GS2 code indicate that the observed turbulence is driven by the electron temperature gradient. These turbulent fluctuations were not observed at the location of an internal transport barrier driven by a negative magnetic shear.

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  • Report No.: PPPL-4395
  • Grant Number: DE-ACO2-09CH11466
  • Office of Scientific & Technical Information Report Number: 951312
  • Archival Resource Key: ark:/67531/metadc931388

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  • March 26, 2009

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  • Nov. 13, 2016, 7:26 p.m.

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  • Dec. 13, 2016, 12:17 p.m.

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Mazzucato, E.; Bell, R. E.; Ethier, S.; Hosea, J. C.; Kaye, S. M.; LeBlanc, B. P. et al. Study of Turbulent Fluctuations Driven by the Electron Temperature Gradient in the National Spherical Torus Experiment, report, March 26, 2009; Princeton, New Jersey. (digital.library.unt.edu/ark:/67531/metadc931388/: accessed August 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.